In general, in power plants (such as nuclear power plants and thermal-electric power plants), petrochemical plants, and the like, pipes for transferring high-temperature and high-pressure steam are installed. With time, these pipes are corroded due to high-temperature and high-pressure steam, whereby the walls of the pipes are thinned.
Such thinning of the walls of pipes may cause pinholes in the pipes with time, resulting in nasty accidents. For this reason, once a year, planned maintenance is performed, whereby wall thinning inspection is performed on pipes and the results of the inspection are recorded and reported.
In a case of performing such wall thinning inspection, if existing insulators have been applied on pipes, finishing metal covers and the insulators of the outer side of the pipes are subsequently removed, and then wall thinning inspection is performed. After the wall thinning inspection is performed, new insulators are attached, and then finishing with the finishing covers is performed.
This manner in which insulators are applied after wall thinning inspection causes a huge amount of waste such as insulators and finishing covers, which results in a waste of an enormous amount of materials. Especially, in a case of applying insulators on elbow or T-joint portions, a higher degree of skill is required as compared to a case of applying insulators on straight pipes, and if the insulators are erroneously applied, thermal notches may be formed, whereby thermal stress may increase and thinning of the walls of the corresponding portions may remarkably proceed, whereby the life of the whole piping apparatus may decrease.
A method for solving that problem has been proposed in Korea Patent No. 10-1184392 (registered on Sep. 13, 2012). In Korea Patent No. 10-1184392 (registered on Sep. 13, 2012), a pipe insulation apparatus includes elbow insulation units, T-joint insulation units, straight-pipe insulation units, and flange insulation units, and each of the insulation units includes two or more segments, and each of the segments is composed of a plurality of insulation layers and is covered with a finishing metal cover.
The finishing cover according to the related art has a structure in which a plurality of assembly segments 55a (or plates) is assembled so as to correspond to the curved surface of an elbow 21 as shown in FIG. 10 of Korea Patent No. 10-1184392 (registered on Sep. 13, 2012). The plurality of assembly segments 55a has bent assembly end portions 55b. Reinforcing connectors 56 have connection end portions 56b bent in the opposition directions to the bending directions of the assembly end portions 55b. The reinforcing connectors 56 are fit on the assembly end portions 55b of the assembly segments 55a and then are compressed in a rolling process or the like, whereby the plurality of assembly segments 55a is connected in a circumferential direction.
However, a process of manufacturing the finishing covers having the above described structure requires a process of bending and connecting the end portions of the assembly segments and the end portions of the reinforcing connectors, and thus is complicated and has a low degree of accuracy, and the reinforcing connectors and the assembly end portions are frequently separated, resulting in defects.